Error：a bytes-like object is required not str

用python3从网上导入的数据类型时bytes不能直接用str的方法，需要decode(‘utf8’)才行。
例子如下：

target_url = ("https://archive.ics.uci.edu/ml/machine-learning-"
"databases/undocumented/connectionist-bench/sonar/sonar.all-data")

data = urllib.request.urlopen(target_url)

#arrange data into list for labels and list of lists for attributes
xList = []
labels = []
for line in data:
    #split on comma
    #这里书上的会报错，因为在python3里读进来时数据是bytes，需要转码之后用str的方法。
    row = line.decode('utf8').strip().split(',')
    xList.append(row)代码片

还是看看stackoverflow吧：

---

1. You opened the file in binary mode:

   with open(fname, ‘rb’) as f: This means that all data read from the file is returned as bytes objects, not str. You cannot then use a string in a containment test:

   if ‘some-pattern’ in tmp: continue You’d have to use a bytes object to test against tmp instead:

   if b’some-pattern’ in tmp: continue or open the file as a textfile
   instead by replacing the ‘rb’ mode with ‘r’.

---

with open(fname, 'rb') as f:
    lines = [x.decode('utf8').strip() for x in f.readlines()]